1. Field of the Invention
This invention relates to laser target illuminator systems and particularly to a simplified and light weight target illuminator that provides both high peak power pulses at a low pulse rate suitable for long range acquisition or tracking and low power pulses at a high pulse rate suitable for short range acquisition or terminal guidance.
2. Description of the Prior Art
Laser target illuminators may be utilized for guidance of missiles or for tracking a target and may function in a system operating either in the active or semi-active state. Active guidance or tracking occurs when both the illuminator and the receiver are on the same missile or at the same station and semi-active guidance or tracking occurs when the illuminator is at one position such as in an aircraft, ship or on the ground and the receiver is at another position such as in a missile or other aircraft. Laser target illuminators may be utilized to provide both tracking or ranging at a relatively long range and may be utilized to provide tracking or ranging at relatively short ranges, such as for terminal guidance or rangefinding. Conventional illuminators use a relatively constant peak pulse power level and are therefore limited in satisfying both the long range acquisition and the short range terminal guidance requirements simultaneously except by using a relatively high average power illuminator with its associated heat dissipation power supply and weight problems. For long range operations, the attenuation of the laser energy by the atmosphere is such that high power pulses are required in order that sufficient energy is reflected back to the receiver while at shorter ranges relatively low amplitude pulses may be utilized. On the other hand, at long ranges target tracking accuracy is not critical and low tracking data rates, and low pulse repetition rates may be tolerated, while at short ranges high tracking data rates and high pulse repetition rates are required. It would be a substantial advantage to the art if a laser illuminator system were developed that would operate well at both long and short ranges and provide suitable data rates for both ranges with the system utilizing a minimum amount of average power and having a minimum amount of complexity.